Magnetic convergence device for use in an in-line type color cathode ray tube

ABSTRACT

A mounting plate having first and second arcuate slits is mounted on the neck portion of an in-line type color cathode ray tube. On both surfaces of the mounting plate are slidably disposed first and second arcuate racks and first and second magnetic convergence units each having an E-shaped convergence core, by means of screws passing through the arcuate slits. First and second pinions geared to the arcuate racks are fixed to one end of first and second shafts rotatably fitted to the mounting plate, the other end of the shafts being fixed to the first and second adjusting wheels.

Unit tates atet [191 Takenalra et al.

MAGNETIC CONVERGENCE DEVICE F OR USE IN AN lN-LHNE TYPE COLOR CATl-lODERAY TUBE Inventors: Shigeo Takenaka; Kazuliiko ldaka; Yuichi Sakamoto,all of Fukaya-shi, Saitama-ken, Japan Assignee: Tokyo Shibauro- ElectricCo., Ltd.,

Kawasaki-shi, Japan Filed: Mar. 17, 1972 Appl. No.: 235,841

Foreign Application Priority Data Mar. 20, 1971 Japan .46/18737 U.S. Cl..335/212, 313/77 Int. Cl ..H01f 7/00 Field of Search ..313/75, 76, 77;

[451 Apr. 10, 1973 [5 6] References Cited UNITED STATES PATENTS 102L4452/1962 Wideroc et a1. .335/210 X 3,305,807 2/1967 Ashley et a1 ..335/210 Primary Examiner-George Harris Attorney-Robert D. Flynn et al.

ABSTRACT A mounting plate having first and second arcuate slits ismounted on the neck portion of an in-line type color cathode ray tube.On both surfaces of the mounting plate are slidably disposed first andsecond arcuate racks and first and second magnetic convergence unitseach having an E-shaped convergence core, by means of screws passingthrough the arcuate slits. First and second pinions geared to thearcuate racks are fixed to one end of first and second shafts rotatablyfitted to the mounting plate, the other end of the shafts being fixed tothe first and second adjusting wheels.

4 Claims, 4 Drawing Figures PATENTEDAFRI 0191s I 3.727. 159

SHEET 1 [IF 2 PATENIEDAPRIOIUYS 3 7, 5

SHEET 2 [IF 2 MAGNETIC CONVERGENCE DEVICE FOR USE IN AN IN-LINE TYPECOLOR CA'IIIODE RAY TUBE This invention relates to a magneticconvergence device for use in an in-line type color cathode ray tube andmore particularly to a magnetic convergence 1 device having first andsecond individually and mechanically adjustable magnetic convergenceunits.

An in-line type color cathode ray tube has recently come into use as acolor cathode ray tube. The in-line type tube generally has threeelectron guns arranged in linear relationship, and the electron beamsemitted from the guns are directed to a fluorescent screen through theneck portion of said tube maintaining the in-line arrangement of saidelectron guns. Among these beams, the central beam is usually for agreen color and the two side beams are for red and blue colors. Topresent a clear and proper color picture over the entire area of thescreen, it is necessary for the three electron beams convergently toimpinge on a given small area of the screen. For this purpose, a dynamicconvergence means and a static convergence means cooperating therewithare generally provided on the outer surface of the neck portion inconnection with the red and blue color electron beams so as toelectrically and magnetically adjust their directions. Further, the redand blue color electron beams should be deflected individually all overthe fluorescent screen so as to obtaina good beam convergence, but noneof the conventional convergence devices has succeeded in effectingproper deflection. 1

Accordingly, it is an object of this invention to provide a magneticconvergence device for use in an inline type color cathode ray tubecapable of adjusting the convergence of multiple electron beamsaccurately and uniformly.

In accordance with this invention, the above-mentioned object canbeachieved by providing a magnetic convergence device for use in anin-line type color cathode ray tube comprising a nonmagnetic mountingplate having first and second arcuate slits and a plurality of splitpieces being clamped by a clamping means so as to fix said mountingplate on the outer surface of the neck portion of said cathode ray tube;first and second magnetic convergence units positioned on one surface ofsaid mounting plate; means for adjustably fitting said magneticconvergence units to permit their displacement along said arcuate slits,each of said magnetic convergence units having a nonmagnetic frame, a

- dynamic convergence electromagnet including an E- to .an embodiment ofthis invention;

FIG. 2 is a plan view taken along line II-II of FIG. 1;

FIG. 3 is a plan view taken along line Ill-III of FIG. 1; and I FIG. 4is a plan view of another embodiment of the invention.

Referring to FIGS. 1 to 3 of the accompanying drawings, there isdisposed a disc-shaped nonmagnetic mounting plate 3 on the outer surfaceof a neck portion 1 of an in-line type color cathode ray tube 2. Themounting plate 3 has a bore 4 provided at the center into which the neckportion 1 is inserted, and a plurality of, for example, six split pieces5 formed integrally with the mounting plate 3 and extending from theinner surface of the bore 4. There is provided a clamping meansconsisting of a clamping band 6 and a bolt 7 for clamping the splitpieces 5 to the neck portion 1. First and second arcuate slits 8 areformed in the mounting plate 3 in concentric relationship with the bore4.

On one surface of the mounting plate 3 facing an electron gun assembly(not shown) disposed at one end part of the neck portion 1 arepositioned first and second arcuate racks 9, which have a curvaturecorresponding to that of the racks, 8 and a width slightly larger thanthat of the slits 9. On the other surface of the mounting plate 3 facinga fluorescent screen (not shown) of the cathode ray tube 2 arepositioned first and second magnetic convergence units 10, which areconnected to the arcuate racks 9 by means of screws 11 passing throughthe arcuate slits 8. Thus, the arcuate racks 9 and magnetic convergenceunits 10 are so fitted to the mounting plate 3 as to slide througharcuate slits 8.

Each of the magnetic convergence units 10 comprises a nonmagneticrectangular frame 12 having a bottom plate 13 connected to the arcuaterack 9, a dynamic convergence electromagnet including an E- shaped core14 and dynamic convergence coils 15 wound thereon, and two disc-shapedpermanent magnets 16 positioned between the cross-piece of the E- shapedcore 14 and frame'12. The magnets 16 are pressed against the cross-pieceof the core 14 by compression coil springs 17.

The electron gun assembly of the in-line type color cathode ray tube 2has three linearly arranged electron guns and consequently the emittedthree electron beams 18, 19 and 20 respectively corresponding to red,green and blue colors are also linearly disposed and further separatedby magnetic shield plates 21 and 22 so as to prevent interaction betweenthe magnetic fields applied to the electron beams 18 to 20. The beams,in particular the beams 18 and 20, are therefore independentlyadjustable and their convergence can be controlled by the magneticconvergence units 10, which create dynamic and static fluxes from thefree ends of the E-shaped cores 14 for deflecting the beams 18 and 20.

First and second pinion 23 are geared to the arcuate racks 9. Each ofthe pinions 23 is fixed to one end of a shaft 24 rotatably mounted on aholder 25 formed on the surface of the mounting plate 3. At the otherend of the shaft 24 is provided an adjusting wheel 26 for rotating thepinion 23.

The peripheral portion of one surface of the adjusting wheels 26 isprovided with a scale 27 for indicating the rotating position of themagnetic convergence units 10 on the mounting plate 3.

In FIGS. 1 to 3, three electron beams 18 to 20 emitted from the linearlyarranged three electron guns travel through the neck portion 1 and aredeflected in the deflection device 28 mounted on .the outer surface ofthe funnel portion 29 of the color cathode ray tube 2 so as toconvergently impinge on the fluorescent screen. In the neck portion 1the red and blue beams 18 and 20 are magnetically subjected todeflection by the magnetic convergence units. The magnetic convergenceis achieved using a dynamic convergence flux obtained by applying analternating current to the coils l5 and a static convergence fluxobtained by adjusting the arrangement of themagnetic poles of the twodiscshaped permanent magnets 16. According to this embodiment, themagnetic convergence is further achieved by mechanically displacing themagnetic convergence units along the arcuate slits-8 through rotation ofthe adjusting wheels 26.

In the magnetic convergence device of FIG. 4, the magnetic convergenceunits 10 are fitted to the mounting plate 3 by screws 30 passing throughthe slits 8. The diameter of the screw head is larger than the width ofthe slit 8 and the diameter of the threaded portion of the screw 30passing through the slit 8 is slightly smaller than the width of theslit 8. Therefore, when all of the I screws 30 are loosened, themagnetic convergence units 10 can be easily displaced along the arcuateslits 8 so as to precisely deflect the electron beams 18 and 20. Theother elements of the embodiment of FIG. 4 are operated in the samemanner as those of FIG. 1 and description thereof is omitted.

What we claim is: v

1. A magnetic convergence device for use in an inline type color cathoderay tube comprising a nonmagnetic mounting plate having first and secondarcuate slits anda plurality of split pieces being clamped by a clampingmeans so as to fix saidmou'nting plateon the outer surface of the neckportion of said cathode ray tube; first and second magnetic convergenceunits positioned on one surface of said mounting plate; and means foradjustably fitting said magnetic convergence units to permit theirdisplacement along said arcuate slits, each of said magnetic convergenceunits having a nonmagnetic frame, a dynamic convergence electromagnetincluding an E-shaped core and two disc- I shaped permanent magnetsassociated with said electromagnet.

2. A magnetic convergence device as claimed in claim 1 wherein saidmeans for adjustably fitting said magnetic convergence units comprisefirst and second arcuate racks positioned on the other surface of saidmounting plate; connecting means for connecting a pair of arcuate racksto a pair ofmagnetic convergence units through said arcuate slits; firstand second pinions geared to said arcuate racks and fixed to one end offirst and second shafts rotatably disposed on said mounting plate; andfirst and second adjusting wheels fixed to the other end of said shafts.

3. A magnetic convergence device as claimed in claim 1 wherein saidmeans for adjustably fitting said magnetic convergence units comprises aplurality of screws for fixing said magnetic convergence units to saidmounting plate through said arcuate slits, the diameter of the head ofthe screw being largerthan the width of the arcuate slit.

4. A magnetic convergence device as claimed in claim 2 wherein saidadjusting wheel is graduated on the periphery to indicate the rotatingposition of said magnetic convergence units on said mounting plate.

UNITED STATES PATENT GFFICE @ERHMCATE or CORRECTION Patent No. 3 7 27 159 Dated April 1 O, 1 973 Inventor(s) Shigeo TAKENAKA et al It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1 between lines 36 and 37 insert heading Summary of theInvention--;

Column 1 line 46, before "means insert --and Column 2, line 7, change"consisting of" to which comprises-;

Column 2 line 1 7 change "9" to 8--;

Column 2, line 51 change "pinion" to pinions-;

Column 4, line 2, change "fitting" to mounting-;

Column line 3 after "units" insert -on said mounting plate;

Column 4, line 10, change "fitting" to -mounting;

Column 4, line 1 1 change "comprise" to comprises-;

Column 4. line 22, change "fitting" to --mounting-;

Column 4, line 26, change "the" (second occurrence) to each-.

Signed and sealed this 18th day of December 1973.

(SEAL) I Attest:

EDWARD 14,, FLETCHER, JR. RENE D. TEGTMEYER Attesting Officer ActingCommissionerof Patents F ORM FO-IOSO (10-69) USCOMM-DC GO376-P69 UGOVERNMENT PRINTING OFFICE I969 O-JGG-335,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 727 159 Dated April 1 O l 973 Invent0r(s) Shigeo TAKENAKA et al It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1 between lines 36 and 37 insert heading Summary of theInvention-;

Column 1 line 46, before "means" insert --and Column 2, line 7, change"consisting of" to which comprises-;

Column 2 line 1 7 change "9" to 8- Column 2 line 51 change "pinion" to--p inions--;

Column 4, line 2, change "fitting" to --mounting line 3 after "units"insert on said mounting plate- Column line 10 Column change "fitting" to-mounting-;

line 22, change "fitting" to ---mounting-;

Column 4 line 1 1 change "comprise" to --comprises;

Column 4 Column line 26, change "the" (second occurrence) to each-.

Signed and sealed this 18th day of December 1973.

(SEAL) Attest:

EDWARD M. FLETCHER, JR. RENE D. 'I EGTMEYER Attesting Officer ActingCommissionerof Patents FORM 90-1050 H0459) USCOMM-DC 60376-P69 5 U.5GOVERNMENT PRINTING OFFICE I959 0"355334,

1. A magnetic convergence device for use in an in-line type colorcathode ray tube comprising a nonmagnetic mounting plate having firstand second arcuate slits and a plurality of split pieces being clampedby a clamping means so as to fix said mounting plate on the outersurface of the neck portion of said cathode ray tube; first and secondmagnetic convergence units positioned on one surface of said mountingplate; and means for adjustably fitting said magnetic convergence unitsto permit their displacement along said arcuate slits, each of saidmagnetic convergence units having a nonmagnetic frame, a dynamicconvergence electromagnet including an E-shaped core and two disc-shapedpermanent magnets associated with said electromagnet.
 2. A magneticconvergence device as claimed in claim 1 wherein said means foradjustably fitting said magnetic convergence units comprise first andsecond arcuate racks positioned on the other surface of said mountingplate; connecting means for connecting a pair of arcuate racks to a pairof magnetic convergence units through said arcuate slits; first andsecond pinions geared to said arcuate racks and fixed to one end offirst and second shafts rotatably disposed on said mounting plate; andfirst and second adjusting wheels fixed to the other end of said shafts.3. A magnetic convergence device as claimed in claim 1 wherein saidmeans for adjustably fitting said magnetic convergence units comprises aplurality of screws for fixing said magnetic convergence units to saidmounting plate through said arcuate slits, the diameter of the head ofthe screw being larger than the width of the arcuate slit.
 4. A magneticconvergence device as claimed in claim 2 wherein said adjusting wheel isgraduated on the periphery to indicate the rotating position of saidmagnetic convergence units on said mounting plate.